Asymmetric catalysis is one of the most powerful methods for accessing a wide range of enantiomerically enriched compounds through the action of a chiral catalyst in a variety of asymmetric reactions. In the last few years, catalytic asymmetric alkylation of carbonyl compounds, especially aldehydes, has achieved substantial interest due to employment of organozinc reagents in the presence of a variety of chiral ligands such as β-amino alcohols, amino thiols and pyridyl alcohols (review by Pu and Yu, Chem. Rev. 2001, 101, 757-824). Such asymmetric organozinc additions allow the synthesis of many chiral alcohols that are valuable precursors for the manufacture of pharmacologically and biologically active compounds.
More recently, a practical application of easily accessible chiral secondary and tertiary aminoalkylnaphthols in asymmetric addition of diethylzinc to aromatic aldehydes has been reported by Liu et al., Org. Lett. 2001, 3, 2733-2735, and by Palmieri et al., Tetrahedron: Asymmetry 2002, 13, 2417-2426. Similarly, a convenient protocol for the asymmetric alkenylation of aldehydes employing a tertiary aminoalkylnaphthol ligand has been described by Chan et al., J. Org. Chemistry 2003, 68, 1589-1590.
However, compared to the well established enantioselective alkylations of aldehydes, the corresponding aryl transfer reactions have not yet reached a high level of utility. Up to now, ligands which have been successfully applied to catalyze aryl transfer reactions with high enantiomeric excess (ee) are relatively rare and difficult to manufacture, e.g., catalysts based upon ligands with planar chirality such as the ferrocene derivative shown below.

Thus, the development of other types of effective chiral ligands is an important challenge in the area of catalytic aryl transfer reactions, in particular, chiral ligands which are highly selective and synthetically easily accessible.